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  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>JS-基础语法</title>
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<body>
  

  <script>
    let a = 20;
    console.log(a);
    alert(a);

    const PI = 3.14;  
    //PI = 888; 在vscode中不会报错，但是浏览器中会报错，因为const声明的常量不能被重新赋值 
    // 报错：Assignment to constant variable  分配给常量变量
    console.log(PI);
  </script>
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